Where it is desired to monitor environmental parameters in remote or hostile environments, such as the ocean or uninhabited terrain, it is known to use local recording of the sensed parameters. The recorded data may then be read out by the person collecting the data by occasional visits to the site to collect the recorded data. The need to make such occasional visits is inconvenient and may expose the collector to danger if the conditions at the recording site are hostile.
Systems utilizing data transmission from remote sites have in the past been costly and required special licensing of the transmitting facility.
A great simplification of the collection of remotely recorded data is found in a description of our presently claimed invention in INTERACTIVE WATER MONITORING SYSTEM ACCESSIBLE BY CORDLESS TELEPHONE, Review of Scientific Instruments, Vol. 56, No. 12, December 1985, incorporated herein by reference.